Velvet ash (Fraxinus velutina Torr.) is a dioecious tree species, which is widely used as a part of urban greeneries in saline land of North China. Female and male trees have different nutrient allocation trade-offs in dioecious species. As the fruit production consumes a lot of nutrients, female F. velutina plants grow slowly and are vulnerable to insects and diseases. Ecological stoichiometry can be used to study the physiological mechanism of the growth difference between female and male plants. The purpose of this study was to compare the seasonal patterns of C, N and P stoichiometry and their trade-offs in different organs of female and male F. velutina plants planted in urban green spaces. The fruit C, N and P contents of female F. velutina plants were all lower than those of leaves in the early growing season, but higher than those of leaves in the middle and late growing season. During most months, the leaf C and P contents of females were higher than those of males, while the leaf N content was lower than that of males, which was consistent with the sex-specific resource requirements for reproduction (i.e., high carbon requirements for ovules and high nitrogen demands for pollen). Compared to the females, there were more significant correlations between the stoichiometric indices (element contents and their ratios) of branches and leaves in male plants, and this difference may be related to the fact that the male plants were not involved in nutritional allocation for fruits. The leaf N/P of F. velutina was lower than 14 in the whole growing season, which indicated N limitation. The female and male plants of F. velutina had different sex-specific resource requirements for sex organ formation.

Wetland restoration has led to land-use changes of coastal zone and also effected on soil nutrient distribution and dynamics. To characterize the differences of typical biogenic elements (C, N and P) distribution and trends of soil induced by wetland restoration policy, we studied two intervention strategies which covered woodland or cropland converted into wetland from four wetland use conditions (ash grove (AG), permanent wetland (PW), wheat field (WF) and seasonal wetland (SW)) in the Yellow River Delta (YRD). The results demonstrated that conversion to permanent wetland showed a more or less significant increase in concentrations and stoichiometric ratios of soil C, N and P, while reclamation of seasonal wetland increased soil N and soil P and the ratio of soil N:P (RNP). We observed the mean soil C concentrations of PW and SW increased by 31.1% and 6.3% in the 0-50cm soil profile separately, compared to their former wetland use, confirming powerful C sequestration of coastal wetlands. PW after 25 years of conversion of woodland to wetland showed an increase in soil C:N (RCN, 25.7%) and C:P (RCP, 30.0%) and SW after 12 years of returning cropland to wetland showed an increase by 17.6% in RCN throughout the soil profile, while similar differences of soil in top 5 cm layers turned out to be even apparent in the studied four wetland use conditions, suggesting the varying of different wetland intervention strategies and implementation period. The underlying changes in nutrient distribution and stoichiometric ratio dynamics are mainly due to C sequestration of wetland and N/P fertilization of reclamation. This brings new insights and helps to increase the knowledge the long-term effect of wetland restoration on soil nutrient distribution and trends in YRD. Understanding these effects can provide sensible policymaking for the conservation and management of coastal wetlands, which is helpful to realize ecological functionality of coastal wetland and achieve carbon neutrality in China.

As a clean and renewable energy source, wind energy offers lower development and utilization costs than solar energy, making it the most promising renewable option. However, the carbon footprint of offshore wind power and its external impacts on cross-regional carbon emissions have not been investigated sufficiently. Using the provinces of Guangdong and Jiangsu as case studies, this study employs socioeconomic and environmental statistical data. It applies the environmentally extended multi-regional input–output (EE-MRIO) method to quantify cross-regional environmental spillover effects associated with offshore wind power development. The findings show that China’s power structure has been continuously optimized, with offshore winds achieving leapfrog growth since 2010. Through a “local consumption” model, offshore wind power in Guangdong and Jiangsu has effectively replaced coal-fired generation, substantially reducing carbon emissions locally and in neighboring areas. Jiangsu has reduced CO₂ emissions by 16.72 million tons annually, and Guangdong by about 7.23 million tons annually. Furthermore, offshore wind development drives the green transformation of upstream industries (e.g., steel, non-ferrous metals, and chemicals). It extends carbon-reduction benefits to resource-rich regions such as the Northwest and North China. As major manufacturing hubs, both provinces lowered the embodied carbon intensity of their export products by using clean electricity, thereby indirectly reducing the national carbon footprint through cross-regional trade. This study offers scientific insights to help policymakers optimize offshore wind layouts, facilitate coordinated regional emission reductions, and advance sustainable energy transitions.